\(H _{ p }=\left[\frac{ V ^2}{\left(\frac{ R }{2}\right)}\right) t =\frac{2 V ^2 t }{ R }\)

Series combination

\(H _s=\left(\frac{ V ^2}{2 R }\right) t \quad \therefore \frac{ H _{ p }}{ H _{ s }}=4\)